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    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
</body>
<script>
        // 打印出下面的数组
        var arr = [1, 2, [3, 4, [5, [2, 9], [8, 0, [6, [7, [12], 6], 5], 1], 1], 5], 123]
    function fun(arr) {
        for (let i in arr) {
            if (Array.isArray(arr[i])) {
                fun(arr[i])
 
            } else {
                console.log(arr[i]);
            }
 
        }
    }
    fun(arr)
</script>
</html>